1. Field of the Invention
The present invention relates to a power supply device, more particularly, to a direct current (DC)-to-DC converter having a boost/buck function and high efficiency.
2. Description of Related Art
Conventionally, to stably and accurately provide a power voltage required by a load (for example, an electronic device), a direct current (DC)-to-DC converter is generally designed to have a boost/buck function. FIG. 1 is a circuit schematic diagram illustrating a conventional DC-to-DC converter 100 having the boost/buck function. Referring to FIG. 1, the DC-to-DC converter 100 includes a transformer TX having an isolation function, a switch SW, a capacitor C, a diode D and a voltage feedback controller VF.
Generally, the voltage feedback controller VF continually detects a power voltage Vpwr received by a load LD, and accordingly generates a control signal CS with a variable duty cycle, so as to boost or buck a DC input voltage Vin. In this way, the DC-to-DC converter 100 can stably/accurately provide the power voltage Vpwr required by the load LD.
However, since the DC-to-DC converter 100 simultaneously achieves the boost and the buck functions mainly through the transformer TX having the isolation function, the transformer TX has to burden all of the output power, so that a size of the transformer TX would be very large, and efficiency thereof is relatively low. Therefore, the DC-to-DC converter 100 is hard to be implemented in a miniaturized electronic device.